Conventionally, there has been known a route search system making a route search by controlling the tolls of toll roads, and so on. For example, Patent Document 1 discloses a route search system capable of preventing anew using the same line within a flat-rate toll road section. The route search system makes a search for a route to the destination on the basis of roadmap data provided with data on a flat-rate section in the attribute of each road link. Further, the system extracts flat-rate toll road links from among road links constituting the searched route, moreover, searches the extracted flat-rate toll road links to thereby detect reuse of the same line therein, and changes the searched route having a road section including the reuse of the same line to a route choosing only the flat-rate toll road. Thus, duplicate payments of the fare can be prevented.
Incidentally, in recent years, in order to reduce the inflow of vehicles to cities to relieve congestion, reduce travel time, and improve the environment, the introduction of a road pricing system establishing flat-rate pay areas and charging vehicles passing through the areas has been promoted. The road pricing system is a system that decides “Toll Time Period,” “Toll Object,” “Charging Amount,” and “Toll Zone,” and charges vehicles subject to regulations by the decision. For example, the road pricing system introduced in London in the U. K. decides that the toll time period is from 7:00 am to 6:30 pm, every weekday (except national holidays), the toll objects are vehicles driven or parked on public roads in the toll zone, the fare is £5 a day not depending on the type of vehicle (buses, taxies, two-wheel vehicles, and emergency vehicles are excepted from the regulation), and the toll zone is Central London.
Patent Document 1: Japanese patent No. 3446555
The route search system disclosed in Patent Document 1 as mentioned above is effective in saving the fare charged to a user in a system charging the user by the number of times the user takes a uniform-rate pay area; however, as in the case of the road pricing system of London, in the case of a system where the amount of money charged is fixed per day and a fixed fare is charged regardless of the number of times a mobile unit enters the area if the entries are made within the fixed period of time, there is a problem that a search of the optimum route where the fare is controlled cannot be implemented.
The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a route search system capable of making a search of the optimum route by controlling bearing of fares when a user employs a flat-rate pay area where a fixed fare is charged regardless of the number of times employed by the user in a fixed period of time.